Traditionally cellular networks have been designed to establish wireless communications links between mobile devices or User Equipments (UEs) and fixed communication infrastructure (for example, base stations, access points, or enhanced NodeBs (eNBs)) which serve users in a wide or local geographic range. A wireless network however can also be implemented by utilizing D2D communication links with the assistance of infrastructure or without the need for deployed access points. A communication network can support devices which can connect both to access points (infrastructure mode) and other D2D-enabled devices. A D2D-enabled device is referred to as a D2D UE.
The D2D communication may be used to implement many kinds of services that are complementary to the primary communication network or provide new services based on the flexibility of the network topology. The LTE D2D multicast communication such as broadcasting or groupcasting has been identified as a potential means for D2D communication where UEs are able to transmit messages to all in-range D2D-enabled UEs or a subset of UEs which are members of particular group. Future public safety networks are expected to require devices to operate in near simultaneous fashion when switching between cellular and D2D communication modes. As a result, there is a need for protocols which can manage D2D communication in these deployment scenarios.